Are bad-ass rims functional ? No. They provide looks.
Are 4 tail pipes functional? No. You can do with two. They just provide looks.
Is 10 different color options functional ? No. They provide looks.
Is M3 badging on the trunk and on the doorsteps functional ? No. Looks.
Are the body shape curves on the sides functional? No. Design/looks.
Are the the curves in the front fender functional? Design/looks.